As used herein, a time-dependent resource is a resource that must be used or consumed within a limited period of time or else it is wasted. Ordinarily, the supply of a time-dependent resource is very difficult to alter, or becomes very difficult to alter as the time for providing the resource nears.
A common example of a time-dependent resource is an airline seat. Basically, each seat on any given flight must be sold or else it will be a wasted resource, from the airline's perspective. If given enough advance notice, the airline might be able to rearrange its flight schedule or add flights here or there. However, at some point, for efficiency reasons all or nearly all of the airline's planes become committed, making further changes very difficult. At that point, some limited accommodations might still be possible, e.g., in cases where an airplane is grounded for mechanical reasons, but large-scale scheduling changes to accommodate last-minute changes in demand simply are not made in practice.
On the other hand, because plans change, people become ill and other intervening circumstances arise, individual consumers often will not know in advance with certainty whether or not they will need, want or even be capable of using a seat on a flight to a particular destination at a particular time. Ideally, the consumer would like a seat to be available to him or her in case it ultimately is needed or desired. Unfortunately, making sufficient capacity available for the highest expected demand would be very expensive in most cases. Accordingly, an airline typically must engage in some guesswork about the actual demand that ultimately will materialize.
Such a lack of information makes it very difficult for the airlines to plan an efficient flight schedule, often resulting in disparities between supply and demand. For similar reasons, the pricing of airline tickets often appears to be erratic and nonsensical. One technique commonly employed by the airlines is to have an advance price (e.g., if a ticket is purchased at least 21 days in advance) and a much higher on-spot price. It is noted that the much-higher on-spot price often is charged even if the airplane has available capacity that otherwise would go unsold. Another common technique is to make available a refundable ticket, usually priced much higher than a non-refundable ticket.
Similar problems exist in other situations. For instance, a table at a restaurant, computer network resources and show tickets all are examples of time-dependent resources that potentially might be needed or wanted by any of a variety of different consumers.
As indicated above, generally only very crude attempts have been made to address the supply and demand problems associated with the pricing and/or reservations of time-dependent resources.